Water heating system



Filed March 31, 1941 INVENTOR. CLARA N OSTERHELD A T TOE/Vf Y Patented Dec, 16, 1941 WATER. HEATING SYSTEM Clark M. Osterheld, Stoughton, Wis., assignor to McGraw Electric Company, poration of Delaware Elgin, 111., a cor- Application March 31, 1941, Serial No. 385,975

Claims.

My invention relates to control systems and particularly to control systems for hot water heaters.

An object of my invention is to provide a system of control for the heater of a hot water tankincluding switching means effective to cause energization of the heater at any time during the day when the tank is less than full of hot water, this condition continuing during times of ordinary loads, and that will be effective to continue energization during periods of heavy loads on other circuits than the heater circuit only in case less than a predetermined fractional part of the water content of the tank is hot.

Other objects of my invention will either be apparent from a description of one form of system embodying my invention or will be set forth in the course of such description and particularly in the appended claims.

In the single figure I have illustrated, generally only, a domestic hot-water tank having associated therewith my improved heating control system.

I have shown a hotwater tank I I which is provided with a cold water inlet pipe and a hot water outlet pipe and which is to be understood as being substantially of the construction now well known in this art.

I provide preferably a single heater I3 and I provide a pair of thermally actuable heater control switches l6 and I1 so mounted on the tank as to be subject to water temperature at two different points on the tank. The switch I6 is connected in series circuit relation to heater I3 and I have shown a flexing bimetal bar l6 for the lower switch H: which is adapted normally to be in electrical engagement with a fixed contact member 2| as long as less than substantially all of the water in the tank is hot but is adapted to move out of engagement with fixed contact 2| when substantially all of the water in the tank is hot.

The upper thermal switch |1 includes a flexing bimetal bar '23 and a fixed contact member 26 and'it is to be understood that the two thermal switches 6 and H are adapted to be in close heat receiving engagement with the tank II. It is evident that the amount of hot water affecting the upper thermal switch |1 will vary with the position of this switch relatively to the height of the tank, all as will be hereinafter set forth.

I provide an electromagnetically actuable switching means 21 embodying a plurality of contact members and adapted to be moved selectively to a plurality of different operating positions. I provide a pair of spaced fixed contact members 26 and 3| and a contact arm 36 normally yieldingly biased into engagement with fixed contact member 6| but adapted to be moved out of engagement therewith and into engagement with fixed contact member 29 by an electromagnet including a coil 36 and a fixed magnetizable core 21 which core 31 is adapted to magnetically energize an armature 69 mounted on the outer end of contact arm 36. Fixed contact member II is connected by a conductor 6| with fixed contact member 2| while contact 26 is connected through a conductor 66 with fixed contact member 26 of the upper thermal switch l1. Contact arm 33 is connected through a conductor 66 with one supply circuit conductor 61.

I have shown a pair of supply circuit conductors 41 and 66 as beingconnected through suitable fuses 6| with two bus bars 63 and 66 mounted on a suitable panel board 61, all in a manner well known in the art. I have illustrated the use of fuses 66, one of which is connected in circuit with conductor 46 and the other of which is connected in circuit with a conductor 6| having one end thereof connected with one terminal of heater l6 and the other end thereof with bus bar 63. The other terminal of heater I3 is connected with the fixed support of bimetal bar I9. I connect the fixed supports of bimetal bars I! and-23 by a conductor 63.

Since I desire to change the operative position of switching means 21 at and during the times of excess load in a predetermined circuit other than the heater circuit of tank I I, I connect coil 66 in series electric circuit with the conductors 66 and Conductor 61 is connected to bus bar 66 through a suitable fuse and I have shown a plurality of incandescent lamps 66, a motor 1| and a plurality of resistors 13 as connected to the other circuit including conductors 66 and 61. Thus the lights 66 might represent a house lighting load, suitable provision being made to separate the lighting circuit from all of the other circuits. The'motor 1| might be considered to represent the motor of'an oil burner, the motor of a refrigerator, or that of a fan motor, it being understood that this is representative only. .The resistors 16 may be considered, for instance, to represent a range load and in order to indicate that the amount of current in this other electric load circuit is variable, I have illustrated the use of a manually operable switch as applied to and connected in circuit with the individual appliance mentioned above. Conductor 66 is connected to one terminal of coil 36, the other terminal of which is connected by a conductor with V the other bus bar 53.

Reference to the single figure of the drawing will show that as long as the load in a second load circuitis below a predetermined value, contact arm 33 of switch 21 is in engagement with contacts, a contact arm selectively movable into engagement with said fixed contacts and norfixed contact member 3| and heater l3 will be energized during all such time in case less than all of the water in the tank is hot through a circuit substantially as follows: From supply circuit conductor 49 through conductor BI, heater I3, through closed thermal switch I5, through conductor H to contact 3|, through contact arm 33 and conductor 45 to busbar 55 and from there to the other supply circuit conductor 41. It is therefore evident that if less than all or substantially less than all of the water in the tank is hot, heater l3 will be energized during all such periods of the day when the value of the current in the other circuit is less than a predetermined amount.

Let it be assumed, for instance, that the other circuit is one including the range heaters and that it is desired to cause deenergization of the I heater l-3 oi the tank in case at least a predeter-,

mined fractional part of the water content of the is hot at the time when the current in said other circuit, traversing the resistors 13, is beyond or above 'a certain value. When the current through coil 35 in said other circuit is beyond said predetermined limit or value, the

, contact arm 33 will be moved so that it is in engagement with fixed contact 29 whereby another circuit through the heater l3 will be energized provided certain other operating conditions are present. This circuit is substantially as follows: from supply circuit conductor 49 to bus comprising an electric circuit having an electric bar 53, through conductor GI and heater l3,- through conductor 63, through the upper thermal switch I'I, (if subject to cold water) through conductor 43 to contact 29, to engaged contact arm 33 and from there through conductor 45 .tobus bar and from there to the other supply circuit conductor 41. The operating conditions necessarily present in case the above described energizing circuit is efieoted by the switching means are that less than a predetermined fractional part of the water content of the tank is hot with the result that upper thermal switch I1 is subject to the temperature of cold water. The. above described operation of my improved system is therefore such that the heater l3 will be energized even during periods of relatively heavy load on another circuit in, say, the house if the amount of hot water in the tank is not sufllcient for ordinary requirements, but if the upper thermal switch I1 is responsive to the temperature of hot water, that is, the tank contains a suflicient amount of hot water. to meet ordinary running requirements, the heater I3 will not be energized during periods of heavy load on another circuit in the house irrespective of when such periods of heavy load occur.

Various modifications may be made in the. system embodying my invention as herein shown and described and all such modifications clearly coming within the scope of the appended claims thereby.

A heater through said auxiliary thermal switch in I mally yieldingly biased into engagement with one of said fixed contacts to cause energization of said heater in case less than all of the water in the tank is hot, a second electric load circuit and means controlled by the current in said second circuit when the current therein exceeds a predetermined value for causing movement of said contact arm into engagement with the other contact to continue energization of the heater in case said thermally-responsive switch is subject to cold water.

. 2. A water heating system for a hot water tank comprising an electric circuit having an electric heater for the tank connected therein, heatercontrol switching means normally'biased into position to effect energization of said heater in case less than all of the water in the tank is hot, a second electric load circuit, and electromagnetic means controlled by an excess load current in said second circuit for continuing energization of said heater if less than a predetermined fractional part of the water in the tank is hot.

3. A water heating system for a hot water tank heater for the tank connected therein, heatercontrol' switching means normally biased into position to effect energizationoi said heater in case less than all of the water in the tank is hot, a second electric load circuit, and electromagnetic means controlled by an excess load current in said second circuit to interrupt the heating circuit of said heater on occurrence of an excess load current in said second circuit when more than a predetermined fractional part of the water in the tank is hot and for continuing energization of said heater if less than said predetermined fractional part of the water in the tank is hot, said energization continuing, under said second circuit overload conditions, until said predetermined fractional part of the ,water in the tank is hot and continuing, under normal load conditions, until substantially all of the water in the tank is hot.

4. A water heating system for a hot water tank comprising an electric circuit having an electric heater for the tank connected therein, a main thermally-actuable heater control switch for deenergizing said heater when substantially all of the water in the tank is hot, an auxiliary thermally-actuable heater control switch for de-' energizing said heater when a predetermined fractional part. of the water in the tank is hot, I

a plural-contact plural-position heater control switchnormally yieldingly biased into one position, electric connections between said switches and said heater to cause energization of said heater when the switch isin its normal position and less than all of the water in the tank is hot, a second electric load circuit and an electromagnet carrying the current flowing in said second circuit and efiective to move said pluralposition switch into its other position when said second circuit is carrying a current of predetermined value to continue energization of said case less than said predetermined fractional part of the water in the tank is hot and until more than said predetermined fractional part or the water in the tank is hot, reduction of the current in said second circuit to below said predetermined value causing return of the plural-position switch to its normal position and energization oi the heater through said main thermallyactuable switch in case less than all of the water in the tank is hot and until substantially all of the water in the tank is hot.

5. A water heating system for a hot water tank comprising a first circuit including an electric heater, a main thermal heater control switch effective to deenergize the heater when substantially all of the water in the tank is hot, an auxiliary thermal heater control switch effective to deenergize the heater when a certain fractional part of the water content of the tank is hot, 9. second circuit and electromagnetically actuated switching means controlled by the current in said second circuit to cause said heater to be energized through said main thermal switch in case the value of the current in said second circuit is below a given value and said main thermal switch is subject to cold water and to cause said heater to be energized through said auxiliary thermal switch in case the value of the current in said second circuit is above said given value and said auxiliary thermal switch is subject to cold water.

CLARK M. OSTERHELD. 

